Cops are investigating after an officer was seen on video repeatedly striking a man prone on the ground. The Chicago Police Department announced this probe Tuesday, according to NBC Chicago.

“We became aware of the video documenting plain clothes officers attempting to arrest a noncompliant offender after a suspected narcotics transaction last night,” the department said in a statement obtained the outlet. “An investigation into the incident has been opened and the matter will be referred to the Independent Police Review Authority for a thorough review of the facts and circumstances of the incident.”

This stems from video recorded by 34-year-old Jermaine Milan‘s family. They say officers arrested him Monday, and footage depicts him pinned to the ground by two officers. One law enforcement official strikes Milan in the head several times, apparently telling him “spit it out.” The family claims he told the suspect “I’ll kill you.”

It’s unclear what Milan allegedly put in his mouth.

The family told WGN-TV that Milan sustained a broken nose, black eye, and injured arm which needed a sling. Stepmother Gloria Nelson said Milan did try to hide something in his mouth, but the officers overreacted. She said she pleaded with him to spit out the object.

Milan has been charged with possession of a controlled substance, obstruction of justice, and aggravated assault.